//
// reference_counted.cpp
// ~~~~~~~~~~~~~~~~~~~~~
//
// Copyright (c) 2003-2018 Christopher M. Kohlhoff (chris at kohlhoff dot com)
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//

#include <boost/asio.hpp>
#include <iostream>
#include <memory>
#include <utility>
#include <vector>
#include <ctime>

using boost::asio::ip::tcp;

// A reference-counted non-modifiable buffer class.
class shared_const_buffer
{
public:
	// Construct from a std::string.
	explicit shared_const_buffer(const std::string& data)
		: data_(new std::vector<char>(data.begin(), data.end())),
		buffer_(boost::asio::buffer(*data_))
	{
	}

	// Implement the ConstBufferSequence requirements.
	typedef boost::asio::const_buffer value_type;
	typedef const boost::asio::const_buffer* const_iterator;
	const boost::asio::const_buffer* begin() const { return &buffer_; }
	const boost::asio::const_buffer* end() const { return &buffer_ + 1; }

private:
	std::shared_ptr<std::vector<char> > data_;
	boost::asio::const_buffer buffer_;
};

class session
	: public std::enable_shared_from_this<session>
{
public:
	session(tcp::socket socket)
		: socket_(std::move(socket))
	{
	}

	void start()
	{
		do_write();
	}

private:
	void do_write()
	{
		std::time_t now = std::time(0);
		shared_const_buffer buffer(std::ctime(&now));

		auto self(shared_from_this());
		boost::asio::async_write(socket_, buffer,
			[this, self](boost::system::error_code /*ec*/, std::size_t /*length*/)
		{
			do_write();
		});
	}

	// The socket used to communicate with the client.
	tcp::socket socket_;
};

class server
{
public:
	server(boost::asio::io_context& io_context, short port)
		: acceptor_(io_context, tcp::endpoint(tcp::v4(), port))
	{
		do_accept();
	}

private:
	void do_accept()
	{
		acceptor_.async_accept(
			[this](boost::system::error_code ec, tcp::socket socket)
		{
			if (!ec)
			{
				std::make_shared<session>(std::move(socket))->start();
			}

			do_accept();
		});
	}

	tcp::acceptor acceptor_;
};

int main(int argc, char* argv[])
{
	try
	{
		if (argc != 2)
		{
			std::cerr << "Usage: reference_counted <port>\n";
			return 1;
		}

		boost::asio::io_context io_context;

		server s(io_context, std::atoi(argv[1]));

		io_context.run();
	}
	catch (std::exception& e)
	{
		std::cerr << "Exception: " << e.what() << "\n";
	}

#ifdef _WIN32
	system("pause");
#endif
	return 0;
}
